It's really strange that interactive access to MOS works, while downloads via
PCA/wget don't. You'll have to go a step back and take PCA out of the equation.
Take a look at the wget examples in article 1199543.1:
https://supporthtml.oracle.com/ep/faces/secure/km/DocumentDisplay.jspx?id=1199543.1&h=Y
Try the example commands listed there to download sample patches. If these work
with the same user/password and patchID which don't work with PCA, it must be a
problem with PCA (it uses a slightly different, more general way to download
files from Oracle).
If the sample commands don't work either, it's on Oracle. Maybe there's some
internal issue with your MOS account, Support Levels, etc.
Martin.